RH302 RHCE (Redhat Certified Engineer) Questions and Answers

Very Tricky question from redhat. Actually question is giving scenario to you to implement quota to neo user. You should apply the quota to neo user on /home that neo user shouldn’t occupied space more than 70K.

1. vi /etc/fstab

LABEL=/home /home ext3 defaults,usrquota 0 0  To enable the quota on filesystem you should mount the filesystem with usrquota for user quota and grpquota for group quota.

2. touch /home/aquota.user  Creating blank quota database file.

3. mount -o remount /home  Remounting the /home with updated mount options. You can verify that /home is mounted with usrquota options or not using mount command.

4. quotacheck -u /home  Initialization the quota on /home

5. edquota –u neo /home  Quota Policy editor

See the snapshot

Disk quotas for user neo (uid 500):

Filesystem blocks soft hard inodes soft hard

/dev/mapper/vo-myvol 2 30 70 1 0 0

Can you set the hard limit 70 and soft limit as you think like 30.

Verify using the repquota /home command.

Questions asking you to install the dialog package from the server. In your Lab FTP server as well as NFS server are configured. You can install either through FTP or NFS.

1. Just Login to server1.example.com through FTP: ftp server1.example.com

2. Enter to pub directory: cd pub

3. Enter to RedHat/RPMS: cd RedHat/RPMS

4. Download the Package: mget dialog-*

5. Logout from the FTP server: bye

6. Install the package: rpm -ivh dialog-*

7. Verify the package either installed or not: rpm -q dialog

You should know about the /etc/inittab file, where default runlevel will define. And Much more runlevel specific Scripts are called here.

Actually that problem will occur if you don’t specify the default runlevel.

Reboot the system

Boot the System on single user mode.

Except for a normal boot of Linux, single-user mode is the most commonly used option. This is the system maintenance mode for experienced Linux administrators. It allows you to perform clean backups and restores to any partitions as needed from local hardware. It also allows you to run administration commands, recover or repair password and shadow password files, run filesystem checks, and so forth.

vi /etc/inittab and Write

id:runlevel:initdefault:

Standard Runlevels in RedHat Enterprise Linux

Runlevel

Description

0

Halt

1

Single-user mode, for maintenance (backups/restores) and repairs

2

Multiuser, without networking

3

Multiuser, with networking

4

Unused

5

X11, defaults to a GUI login screen. Logins bring the user to a GUI desktop.

6

Reboot (never set initdefault in /etc/inittab to this value!)

We know that every files/directories are owned by certain user and group. And Permissions are defines to owner user, owner group and other.

-rwxr-x---  Full permission to owner user, read and write to owner group and no permission to others.

According to question: We should give the full permission to user user1 without changing the previous permission.

ACL (Access Control List), in ext3 file system we can give permission to certain user and certain group without changing previous permission. But that partition should mount using acl option. Follow the steps

vi /etc/fstab

/dev/hda14 /data ext3 defaults,acl 0 1

Either Reboot or use: mount –o remount /data

setfacl –m u:user1:rwx /data

Verify using: getfacl /data

Do the following steps as:

1. vi /etc/dhcpd.conf

ddns-update-style none;

option routers 192.168.0.1;

option domain-name “example.com”;

option domain-name-servers 192.168.0.254;

default-lease-time 21600;

max-lease-time 43200;

subnet 192.168.0.0 netmask 255.255.255.0

{

range 192.168.0.1 192.168.0.254;

host dns1 {

hardware ethernet 00:50:FC:98:8D:00;

fixed-address 192.168.0.254;

}

host dns2 {

hardware ethernet 00:50:FC:98:8C:00;

fixed-address 192.168.0.253;

}

}

/etc/dhcpd.conf file is used to configure the DHCP. Some global options i.e Gateway, domainname, DNS server specified using option keyword. To assign as static ip from dhcp server, required the mac address of interface.

2. service dhcpd start | restart

Do the following steps as:

1. vi /var/named/chroot/etc/named.conf

acl localnet { 192.168.0.0/24; };

options {

allow-query { localnet; };

};

2. service named restart | start

allow-query is a global option on /var/named/chroot/etc/named.conf , specifies an address match list of hosts allowed to query this server. If this option is not set, any host can query the server.

According to question, log server is already configured. We have to configure the mail, web and dns server for log redirection.

In mail, web and dns server:

1. vi /etc/syslog.conf

mail.* @logserveraddress

2. service syslog restart

mail is the facility and * means the priority. It sends all logs of mail service to mail into log server.

Do the following steps as:

1. vi /etc/hosts.deny

dovecot:ALL EXCEPT .example.com EXCEPT station20.example.com

We can secure the services using tcp_wrappers. There are main two files, /etc/hosts.allow and /etc/hosts.deny.

There will be three stage access checking

-Is access explicitly permitted? Means permitted from /etc/hosts.allow?

- Otherwise, Is access explicitly denied? Means denied from /etc/hosts.deny?

- Otherwise, by default permit access if neither condition matched.

To deny the services we can configure /etc/hosts.deny file using ALL and EXCEPT operation. Pattern of /etc/hosts.allow and /etc/hosts.deny file is:

Demon_list:client_list:options

In Client list can be either domain name or IP address.

At exam Lab example.com domain resides on 192.168.0.0/24 Network and cracker.org resides on 192.168.1.0/24 Network.

1. vi /etc/squid/squid.conf

#detault:

http_port 8080

#Recommended minimum configuration:

# Near the src acl src section

acl allownet src 192.168.0.0/255.255.255.0

acl denynet src 192.168.1.0/255.255.255.0

#Default:

# http_access deny all

#Under Here http_access allow allownet

http_access deny denynet

2. service squid start

3. chkconfig squid on

squid is a proxy caching server, using squid we can share the internet, block the internet, to certain network. First we should define the port for squid, the standard port for squid is 3128. We can run squid on different port by specifying http_port portnumber.

Do the following steps as:

ftp ftp.server1.example.com

Download the www.html

move the downloaded file into /var/www/html

Rename the file into index.html

Check using links http://stationx.example.com

/var/www/html is the default directory for httpd service. Index.html is the default directory index. To set the default page without configuring virtualhost copy the file as a index.html in /var/www/html.

Do the following steps as:

1. vi /etc/squid/squid.conf

#detault:

http_port 8080

#Recommended minimum configuration:

# Near the src acl src section

acl allownet src 192.168.0.0/255.255.255.0

acl msnnet dstdomain .msn.com

#Default:

# http_access deny all

#Under Here http_access deny msnnet

http_access allow allownet

2. service squid start

3. chkconfig squid on

squid is a proxy caching server, using squid we can share the internet, block the internet, to certain network. First we should define the port for squid, the standard port for squid is 3128. We can run squid on different port by specifying http_port portnumber.

To block or allow the Internet access to hosts, we should create the acl (Access Control List). In this file we can specify only the IP address.

Example: acl aclname src IP/Netmask After creating acl we can block or allow the Internet to specified acl.

http_access allow | deny alcname

Do the following steps as:

1. vi /etc/security/time.conf

login;*;user9|user10;SuMoFri1200-1400

2. vi /etc/pam.d/login

account required pam_time.so

For Time based authentication, we should configured in /etc/security/time.conf

Syntax of /etc/security/time.conf

services;ttys;users;times

services

is a logic list of PAM service names that the rule applies to.

ttys

is a logic list of terminal names that this rule applies to.

users

is a logic list of users to whom this rule applies.

times

the format here is a logic list of day/time-range entries the days are specified by a sequence of two character entries, MoTuSa for example is Monday Tuesday and Saturday. Note that repeated days are unset MoMo = no day, and MoWk = all weekdays bar Monday. The two character combinations accepted are

Mo Tu We Th Fr Sa Su Wk Wd Al

the last two being week-end days and all 7 days of the week respectively. As a final example, AlFr means all days except Friday.

pam_time modules checks the file /etc/security/time.conf for authentication. So, we should call the pam_time modules in /etc/pam.d/login.

1. vi /etc/resolv.conf

Write : nameserver 192.168.0.254

Think while Problems occurred on booting System on Runlevel 5 (X Window).

/tmp is full or not

Quota is already reached

Video card or resolution or monitor is misconfigured.

xfs service is running or not.

Do These:

1. df –h /tmp  /tmp is full remove the unnecessary file

quota username  if quota is already reached remove unnecessary file from home directory.

Boot the System in runlevel 3.  you can pass the Kernel Argument from boot loader.

Use command: system-config-display  It will display a dialog to configure the monitor, Video card, resolution etc.

Set the Default Runlevel 5 in /etc/inittab

id:5:initdefault:

6. Reboot the System you will get the GUI login Screen.

This is boot related problem. There will be same questions repeated two times but problem is different.

First When you restart the system you will get the Error:

mount: error 15 mounting ext3

mount: error 2 mounting none

switchroot: mount failed: 22

umount /initrd/dev/: 2

Kernel Panic: no syncing: Attempted to kill init !

This error occurred in your system before showing welcome redhat linux. That means problem in grub boot loader.

Restart the System

Check the grub boot loader configuration by pressing e shortcut key.

You will see like:

root (hd0,0)

kernel /vmlinuz-2.6.9-5.EL ro root= / rhgb quiet

initrd /initrd-2.6.9-5.EL.img

OR

root (hd0,0)

kernel /vmlinuz-2.6.9-5.EL ro root=LABEL=/root rhgb quiet

initrd /initrd-2.6.9-5.EL.img

Then Edit Boot loader to make like

root (hd0,0)

kernel /vmlinuz-2.6.9-5.EL ro root=LABEL=/ rhgb quiet

initrd /initrd-2.6.9-5.EL.img

Check all lines and edit as same as above. Press b to boot the system

After booting the system you should correct the /etc/grub.conf file.

Do the following steps as:

Use fdisk /dev/hda  To create new partition.

Type n  For New partitions

It will ask for Logical or Primary Partitions. Press l for logical.

It will ask for the Starting Cylinder: Use the Default by pressing Enter Key.

Type the Size: +100M  You can Specify either Last cylinder of Size here.

Press P to verify the partitions lists and remember the partitions name.

Press w to write on partitions table.

Either Reboot or use partprobe command.

Use mkfs –t ext3 /dev/hda?

Or

mke2fs –j /dev/hda?  To create ext3 filesystem.

vi /etc/fstab

Write:

/dev/hda? /data ext3 defaults 0 0

Verify by mounting on current Sessions also:

mount /dev/hda? /data

Do the following steps as:

1. rpm -ivh ftp://server1.example.com/pub/updates/kernel-2.6.19-11.i686.rpm

2. vi /etc/grub.conf

default=1  Change this value to 1

timeout=5

splashimage=(hd0,0)/grub/splash.xpm.gz

hiddenmenu

title Red Hat Enterprise Linux ES (2.6.19-11)

root (hd0,0)

kernel /vmlinuz-2.6.19-11.EL ro root=LABEL=/ rhgb quiet

initrd /initrd-2.6.19-11.EL.img

title Red Hat Enterprise Linux ES (2.6.9-5.EL)

root (hd0,0)

kernel /vmlinuz-2.6.9-5.EL ro root=LABEL=/ rhgb quiet

initrd /initrd-2.6.9-5.EL.img

According question that kernel is available to anonymous user. You can directly install from the ftp server using rpm command.

When you install the kernel, it will write on /etc/grub.conf file. You can set the default kernel by changing the default value. See on the output of /etc/grub.conf file that new kernel is on first title so it’s index is 0 and previous kernel’s index is 1.

Do the following steps as:

1. Insert the CD on CD-ROM and start the system.

2. In Boot: Prompt type linux askmethod

3. It will display the language, keyboard selection.

4. It will ask you for the installation method.

5. Select the NFS Image from the list

6. It will ask the IP Address, Net mask, Gateway and Name Server. Select Use

Dynamic IP Configuration: because DHCP Server will be configured in your exam lab.

7. It will ask for the NFS Server Name and Redhat Enterprise Linux Directory.

Specify the NFS Server: 172.24.254.254

Directory: /var/ftp/pub

8. After Connecting to the NFS Server Installation start in GUI. Go up to the partition screen by selecting the different Options.

9. Create the partition According to the Question because Size and what-what partition should you create at installation time is specified in your question

10. Create the two RAID partitions having equal size of remaining all free space.

11. Click on RAID button

12. Type mount point /data

13. Select RAID Level 0

14. Click on ok

15. Then select the MBR Options, time zone and go upto package selections.

It is another Most Important Time of installation. Due to the time limit, you should care about the installation packages. At Exam time you these packages are enough.

X-Window System

GNOME Desktop

(these two packages are generally not required)

Administration Tools.

System Tools

Windows File Server

FTP Servers

Mail Servers

Web Servers

Network Servers

Editors

Text Based Internet

Server Configuration Tools

Base

Printing Supports

When installation will complete, your system will reboot. Jump for another Question.

Do the following steps as:

1. Open the Browser and type the above URL.

2. Fill the form as required all information.

Do the following steps as:

Login as a root user

cat > schedule.txt

30 05 * * * /bin/echo “Hello”

3. crontab –u david schedule.txt

4. service crond restart

The cron system is essentially a smart alarm clock. When the alarm sounds, Linux runs the commands of your choice automatically. You can set the alarm clock to run at all sorts of regular time intervals. Alternatively, the at system allows you to run the command of your choice once, at a specified time in the future.

Red Hat configured the cron daemon, crond. By default, it checks a series of directories for jobs to run, every minute of every hour of every day. The crond checks the /var/spool/cron directory for jobs by user. It also checks for scheduled jobs for the computer under /etc/crontab and in the /etc/cron.d directory.

Here is the format of a line in crontab. Each of these columns is explained in more detail:

#minute, hour, day of month, month, day of week, command

*        *     *             *      *            command

Entries in a crontab Command Line

Field

Value

Minute

0-59

Hour

Based on a 24-hour clock; for example, 23 = 11 p.m.

Day of month

1-31

Month

1-12, or jan, feb, mar, etc.

Day of week

0-7; where 0 and 7 are both Sunday; or sun, mon, tue, etc.

Command

The command you want to run

Do the following steps as:

1. Go to on that directory where you want to restore.

2. restore –rf /dev/st0

To restore from backup we use the restore command. Here backup will restore from /dev/st0 on current Directory.

Do the following steps as:

rpm -ivh ftp://server1.example.com/pub/kernel-hugemem-*

2. vi /etc/grub.conf

Set the default to new kernel

default=0

Example of /etc/grub.conf

default=0

timeout=5

splashimage=(hd0,0)/grub/splash.xpm.gz

hiddenmenu

title Red Hat Enterprise Linux ES (2.6.9-5.ELhugemem)

root (hd0,0)

kernel /vmlinuz-2.6.9-5.ELhugemem ro root=LABEL=/1 rhgb quiet

initrd /initrd-2.6.9-5.ELhugemem.img

title Red Hat Enterprise Linux ES (2.6.9-5.EL)

root (hd0,0)

kernel /vmlinuz-2.6.9-5.EL ro root=LABEL=/1 rhgb quiet

initrd /initrd-2.6.9-5.EL.img

rpm command is used to install, update and remove the rpm package. -ivh option is install, verbose, and display the hash mark.

Do the following steps as:

1. useradd eric

Very tricky question given to you that this user should not belongs to sysadmin group.

Steps of Creating LVM:

Physical Disk1

Physical Disk2

Physical Disk3

Physical Volume

Volume Group

Logical Volume 1

Logical Volume 2

Logical Volume 3

1. pvcreate /dev/hda8 /dev/hda9 /dev/hda10

 pvdisplay command is used to display the information of physical volume.

2. vgceate test0 /dev/hda8 /dev/hda9 /dev/hda10

 vgdisplay command is used to display the information of Volume Group.

3. lvcreate –L 250M –n testvolume1 test0

 lvdisplay command is used to display the information of Logical Volume.

4. lvcreate –L 250M –n testvolume2 test0

5. mkfs –t ext3 /dev/test0/testvolume1

6. mkfs –t ext3 /dev/test0/testvolume2

7. mkdir /lvtest1

8. mkdir /lvtest2

9. mount /dev/test0/testvolume1 /lvtest1

10. mount /dev/test0/testvolume2 /lvtest2

11. vi /etc/fstab

/dev/test0/testvolume2 /lvtest2 ext3 defaults 0 0

/dev/test0/testvolume1 /lvtest1 ext3 defaults 0 0

To create the LVM( Logical Volume Manager) we required the disks having ‘8e’ Linux LVM type. First we should create the physical Volume, then we can create the Volume group from disks belongs to physical Volume. lvcreate command is used to create the logical volume on volume group. We can specify the size of logical volume with –L option and name with -n option.

Do the following steps as:

1. Create the repository file

#vi /etc/yum.repos.d/server1.repo

[station?]

name=station?

baseurl=ftp://server1.example.com/pub/

enabled=1

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release

# yum install < packagename >

Do the following steps as:

useradd user1

useradd user2

useradd user3

passwd user1

passwd user2

passwd user3

We create the user using useradd command and we change the password of user using passwd command. If you want to set the blank password use: passwd -d username.

Do the following steps as:

cat > schedule

*/2 * * * * /bin/echo “Hello World” > /dev/tty8

crontab schedule

Verify using: crontab –l

service crond restart

Cron helps to schedule on recurring events. Pattern of Cron is:

Minute Hour Day of Month Month Day of Week Commands

0-59 0-23 1-31 1-12 0-7 where 0 and 7 means Sunday.

Note * means every. To execute the command on every two minutes */2.

To add the scheduled file on cron job: crontab filename

To List the Cron Shedule: crontab –l

To Edit the Schedule: crontab –e

To Remove the Schedule: crontab –r

Do the following steps as:

vi /etc/auto.master

/mnt /etc/auto.misc --timeout=50

vi /etc/auto.misc

data -rw,soft,intr server1.example.com:/data

service autofs restart

chkconfig autofs on

When you mount the other filesystem, you should unmount the mounted filesystem, Automount feature of linux helps to mount at access time and after certain seconds, when user unaccess the mounted directory, automatically unmount the filesystem.

/etc/auto.master is the master configuration file for autofs service. When you start the service, it reads the mount point as defined in /etc/auto.master.

Do the following steps as:

1. Insert the CD on CD-ROM and start the system.

2. In Boot: Prompt type linux askmethod

3. It will display the language, keyboard selection.

4. It will ask you for the installation method.

5. Select the NFS Image from the list

6. It will ask the IP Address, Net mask, Gateway and Name Server. Select Use

Dynamic IP Configuration: because DHCP Server will be configured in your exam lab.

7. It will ask for the NFS Server Name and Redhat Enterprise Linux Directory.

Specify the NFS Server: 172.24.254.254

Directory: /var/ftp/pub

8. After Connecting to the NFS Server Installation start in GUI. Go up to the partition screen by selecting the different Options.

9. Create the partition According to the Question because Size and what-what partition should you create at installation time is specified in your question

10. Create the two RAID partitions having equal size of remaining all free space.

11. Click on RAID button

12. Type mount point /document

13. Select RAID Level 0

14. Click on ok

15. Then select the MBR Options, time zone and go upto package selections.

It is another Most Important Time of installation. Due to the time limit, you should care about the installation packages. At Exam time you these packages are enough.

X-Window System

GNOME Desktop

(these two packages are generally not required)

Administration Tools.

System Tools

Windows File Server

FTP Servers

Mail Servers

Web Servers

Network Servers

Editors

Text Based Internet

Server Configuration Tools

Printing Supports

When installation will complete, your system will reboot. Jump for another Question.

Do the following steps as:

useradd username

passwd username

usermod -e “date”

example: usermod -e “12 Feb 2006” user4

Verify: chage –l user4

We can control the services for current session and for next reboot time. For current Session, we use service servicename start or restart or stop or status. For automatically at next reboot time:

chkconfig servicename on or off

eg: chkconfig nfs on

chkconfig portmap on

or

ntsysv

Select the nfs and portmap services.

Reboot the system and identify whether services are running or not.

In Network problem think to check:

IP Configuration: use ifconfig command either IP is assigned to interface or not?

Default Gateway is set or not?

Hostname is set or not?

Routing problem is there?

Device Driver Module is loaded or not?

Device is activated or not?

Check In this way:

use ifconfig command and identify which IP is assigned or not.

cat /etc/sysconfig/network  What, What is written here. Actually here are these parameters.

NETWORKING=yes or no

GATEWAY=x.x.x.x

HOSTNAME=?

NISDOMAIN=?

Correct the file

Use netconfig command

Either Select Automatically from DHCP or assign the static IP

Use service network restart or start command

Now try to ping it will work.

You should know about the /etc/inittab file, where default runlevel will define. And Much more runlevel specific Scripts are called here.

Actually that problem will occur if you don’t specify the default runlevel.

Reboot the system

Boot the System on single user mode.

Except for a normal boot of Linux, single-user mode is the most commonly used option. This is the system maintenance mode for experienced Linux administrators. It allows you to perform clean backups and restores to any partitions as needed from local hardware. It also allows you to run administration commands, recover or repair password and shadow password files, run filesystem checks, and so forth.

vi /etc/inittab and Write

id:runlevel:initdefault:

Standard Runlevels in RedHat Enterprise Linux

Runlevel

Description

0

Halt

1

Single-user mode, for maintenance (backups/restores) and repairs

2

Multiuser, without networking

3

Multiuser, with networking

4

Unused

5

X11, defaults to a GUI login screen. Logins bring the user to a GUI desktop.

6

Reboot (never set initdefault in /etc/inittab to this value!)

Do the following steps as:

1. Verify the File whether Shared or not ? : cat /etc/exports

2. Start the nfs service: service nfs start

3. Start the portmap service: service portmap start

4. Make automatically start the nfs service on next reboot: chkconfig nfs on

5. Make automatically start the portmap service on next reboot: chkconfig portmap on

6. Check default firewall is running in your system

# service iptables status

#iptables –F

#service iptables stop

#chkconfig iptables off

6. Verify Either sharing or not: showmount –e localhost

You will see that some shared directory will display

Maintenance mode also known as emergency mode. System boots on emergency mode when file system error occurred. It is due to unknown partition, bad filesystem specified in /etc/fstab. To slove follow the steps

Give the Root password

fdisk –l  Verify the Number of parations.

Identify the Root partition, e2label /dev/hda1, e2label /dev/hda2…..

Remount the root partation on rw mode: mount –o remount,defaults /dev/hda6 /

vi /etc/fstab

Correct all partitions, mount point, mount options, file system etc.

6. Press ctrl+d

Do the following steps as:

1. First check the size of Logical Volume: lvdisplay /dev/vo/myvol

2. Increase the Size of Logical Volume: lvextend -L+121M /dev/vo/myvol

3. Make Available the size on online: ext2online /dev/vo/myvol

4. Verify the Size of Logical Volume: lvdisplay /dev/vo/myvol

5. Verify that the size comes in online or not: df -h

We can extend the size of logical Volume using the lvextend command. As well as to decrease the size of Logical Volume, use the lvresize command. In LVM v2 we can extend the size of Logical Volume without unmount as well as we can bring the size of Logical Volume on online using ext2online command.

At exam time read the Lab Scenario carefully. Actually there are two different networks one is 192.168.0.0/24 where your system resides know as example.com domain and another is 192.168.1.0/24 know as cracker.org domain.

One server named sever1.example.com having 192.168.0.254 and 192.168.1.254 is running in your exam. If you make a gateway to that server, you will can ping because IP forwarding is enabled on that server.

1. vi /etc/sysconfing/network

NETWORKING=yes

HOSTNAME=station?.example.com

GATEWAY=192.168.0.254

2. service network restart

Or

1. vi /etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE=eth0

ONBOOT=yes

BOOTPROTO=static

IPADDR=X.X.X.X

NETMASK=X.X.X.X

GATEWAY=192.168.0.254

2. ifdown eth0

3. ifup eth0

Note: If gateway is specified in both file, default gateway takes from interface specific file.

While you load the X Window System, you will get the problem. Problem may caused by different error.

1. Check the /tmp is full ?

2. Check your quota, hard limit is already crossed ?

3. Check xfs service is running ?

4. Configure the Video card, Resolution, monitor type using: system-config-display (Most Probably in Redhat exam)

5. Edit the /etc/inittab to set default runlevel 5.

id:5:initdefault:

After completing the Boot loader problem, you will boot the system, but it goes to emergency mode. Remember that if System boots on Emergency mode that means file system problem.

You will get the Shell, remount the / filesystem with read and write mode.

1. First Find out the / filesystem using e2lable /dev/hda1, e2lable /dev/hda2 etc

2. mount –o remount,defaults /dev/hda? /

3. vi /etc/fstab

You will get like:

/root / ext3 defaults 1 1

or / /root ext3 defaults 1 1

4. Edit the file like:

/ / ext3 defaults 1 1

5. Configure the /etc/grub.conf file if just booting system by editing grub from grub prompt.

6. Reboot the system.

Very Easy question, nameserver is specified in question,

1. vi /etc/resolv.conf

nameserver 192.168.0.254

2. host server1.example.com

Do the following steps as:

1. vi /etc/mail/local-host-names

example.com

2. vi /etc/mail/sendmail.mc

dnl # DEAMON_OPTIONS(`Port=smtp,Addr=127.0.0.1,Name=MTA`)dnl

3. m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf

4. vi /etc/mail/access

192.168.0 RELAY

@cracker.org REJECT

5. service sendmail start | restart

6. chkconfig dovecot on

7. vi /etc/dovecot.conf

protocols = pop3 pop3s imap imaps

8. service dovecot start | restart

9. chkconfig dovecot on

10. vi /etc/aliases

user5: user2

11. newaliases

/etc/mail/local-host-names file contains the aliases to hostname. Mail server program reads the /etc/mail/sendmail.cf. To change the configuration on mail server, we should edit the /etc/mail/sendmail.mc file and should generate the sendmail.cf using m4 command.

By default sendmail server allows to connect to local host only. So we should edit the /etc/mail/sendmail.mc file to allow connect to other hosts.

By default sendmail server will not forward mail. we should specify on /etc/mail/access to relay or to block mail coming from domain or network or individual email address.

By default dovecot service start only the imap protocol. To start pop protocol with dovecot, we should write in /etc/dovecot.conf file.

Using /etc/aliases file we can map the user name to send mail of one user to another user. To rebuild database we use the newaliases command.

Do the following steps as:

1. vi /etc/exports

/local *.example.com(rw,sync) trusted.cracker.org(ro,sync)

service nfs start | restart

service portmap start | restart

chkconfig nfs on

chkconfig portmap on

In Linux to share the data we use the /etc/exports file. Pattern is:

Path client(permission)

Shared Directory Path, Client can be single host or domain name or ip address. Permission should specify without space with client lists in parentheses. NFS is RPC service so portmapper service should restart after starting the nfs service. We can specify multiple clients’ list separating by space with different shared option.

Do the following steps as:

1. vi /etc/security/time.conf

login;*;user15|user16;Sa0000-2400

2. vi /etc/pam.d/login

account required pam_time.so

For Time based authentication, we should configured in /etc/security/time.conf

Syntax of /etc/security/time.conf

services;ttys;users;times

services

is a logic list of PAM service names that the rule applies to.

ttys

is a logic list of terminal names that this rule applies to.

users

is a logic list of users to whom this rule applies.

times

the format here is a logic list of day/time-range entries the days are specified by a sequence of two character entries, MoTuSa for example is Monday Tuesday and Saturday. Note that repeated days are unset MoMo = no day, and MoWk = all weekdays bar Monday. The two character combinations accepted are

Mo Tu We Th Fr Sa Su Wk Wd Al

the last two being week-end days and all 7 days of the week respectively. As a final example, AlFr means all days except Friday.

pam_time modules checks the file /etc/security/time.conf for authentication. So, we should call the pam_time modules in /etc/pam.d/login.

Do the following steps as:

1. vi /etc/exports

/data *.example.com(rw,sync)

2. service nfs start | restart

3. service portmap start | restart

4. chkconfig nfs on

5. chkconfig portmap on

In Linux to share the data we use the /etc/exports file. Pattern is:

Path client(permission)

Shared Directory Path, Client can be single host or domain name or ip address. Permission should specify without space with client lists in parentheses. NFS is RPC service so portmapper service should restart after starting the nfs service.

After completing the Boot loader problem, you will boot the system, but it goes to emergency mode. Remember that if System boots on Emergency mode that means file system problem.

You will get the Shell, remount the / filesystem with read and write mode.

1. First Find out the / filesystem using e2lable /dev/hda1, e2lable /dev/hda2 etc

2. mount –o remount,defaults /dev/hda? /

3. vi /etc/fstab

You will get like:

/root / ext3 defaults 1 1

or / /root ext3 defaults 1 1

4. Edit the file like:

/ / ext3 defaults 1 1

5. Configure the /etc/grub.conf file if just booting system by editing grub from grub prompt.

6. Reboot the system.

Do the following steps as:

1. First check the size of Logical Volume: lvdisplay /dev/vo/myvol

2. Increase the Size of Logical Volume: lvextend -L+121M /dev/vo/myvol

3. Make Available the size on online: resize2fs /dev/vo/myvol

4. Verify the Size of Logical Volume: lvdisplay /dev/vo/myvol

5. Verify that the size comes in online or not: df -h

We can extend the size of logical Volume using the lvextend command. As well as to decrease the size of Logical Volume, use the lvresize command. In LVM v2 we can extend the size of Logical Volume without unmount as well as we can bring the actual size of Logical Volume on online using ext2online command.

It is due to either default runlevel or runlevel specific scripts.

id:?:initdefault:  Where default runlevel is specified. It shouldn’t be 6.

l3:3:wait:/etc/rc.d/rc 6  It reads the scripts of runlevel 6 while booting system on rulevel 3.

It should be like:

si::sysinit:/etc/rc.d/rc.sysinit

l0:0:wait:/etc/rc.d/rc 0

l1:1:wait:/etc/rc.d/rc 1

l2:2:wait:/etc/rc.d/rc 2

l3:3:wait:/etc/rc.d/rc 3 Should be like this

l4:4:wait:/etc/rc.d/rc 4

l5:5:wait:/etc/rc.d/rc 5

l6:6:wait:/etc/rc.d/rc 6

Do the following steps as:

1. rpm –ivh ftp://server1/example.com/pub/updates/zsh-*

or

1. Login to ftp server : ftp ftp://server1.example.com using anonymous user.

2. Change the directory: cd pub and cd updates

3. Download the package: mget zsh-*

4. Quit from the ftp prompt : bye

5. Install the package

6. rpm -ivh zsh-*

7. Verify either package is installed or not : rpm -q zsh

Very Easy question, nameserver is specified in question,

1. vi /etc/resolv.conf

nameserver 192.168.0.254

2. host server1.example.com

Do the following steps as:

1. vi /etc/hosts.deny

sshd:ALL EXCEPT .example.com

or

1. vi /etc/hosts.deny

sshd:ALL

2. vi /etc/hosts.allow

sshd:.example.com

We can secure the services using tcp_wrappers. There are main two files, /etc/hosts.allow and /etc/hosts.deny.

There will be three stage access checking

- Is access explicitly permitted? Means permitted from /etc/hosts.allow?

- Otherwise, Is access explicitly denied? Means denied from /etc/hosts.deny?

- Otherwise, by default permit access if neither condition matched.

To deny the services we can configure /etc/hosts.deny file using ALL and EXCEPT operation. Pattern of /etc/hosts.allow and /etc/hosts.deny file is:

Demon_list:client_list:options

In Client list can be either domain name or IP address.

Do the following steps as:

vi /etc/mail/virtusertable

@my133t.org marion

# service sendmail restart

/etc/mail/virtusertable file is used to send the mail coming for virtual user to real user. According to question, all mail to cracker.org should get by eric user so

@my133t.org eric : Which sends all mail of cracker.org to eric user.

Do the following steps as:

1. vi /etc/mail/local-host-names

example.com

2. vi /etc/mail/sendmail.mc

dnl # DEAMON_OPTIONS(`Port=smtp,Addr=127.0.0.1,Name=MTA`)dnl

MASQUERADE_AS(`example.com')dnl

define(`SMART_HOST',`smtp.abc.com')

3. m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf

4. vi /etc/mail/virtusertable

info@example.com admin@example.com

5. vi /etc/mail/access

192.168.0 RELAY

/etc/mail/local-host-names file contains the aliases to hostname. Mail server program reads the /etc/mail/sendmail.cf. To change the configuration on mail server, we should edit the /etc/mail/sendmail.mc file and should generate the sendmail.cf using m4 command.

By default sendmail server allows to connect to local host only. So we should edit the /etc/mail/sendmail.mc file to allow connect to other hosts.

By default sendmail server will not forward mail. We should specify on /etc/mail/access to relay or to block mail coming from domain or network or individual email address.

To masquerade the address, MASQUERADE_AS option is in /etc/mail/sendmail.mc. SMART_HOST deliver all local mail locally and outgoing mail through another mail server.

/etc/mail/virtusertable file is used map virtual address to real address.

Eg.

info@example.com user1@example.com

enquiry@example.com admin@abc.com

Do the following steps as:

1. vi /etc/httpd/conf/httpd.conf

< VirtualHost 192.100.0.1 >

ServerName www.abc.com

DocumentRoot /var/www/abc/

< Directory /var/www/abc >

Order Allow, Deny

Allow from .example.com

< /Directory >

DirectoryIndex index.html

ServerAdmin webmaster@abc.com

ErrorLog logs/error_abc.logs

CustomLog logs/custom_abc.logs common

< /VirtualHost >

2. Create the directory and index page on specified path. (Index page can download from ftp://server1.example.com at exam time)

Check the SELinux context of index page , should like this:

-rw-r--r-- root root system_u:object_r:httpd_sys_content_t /var/www/html/index.html

If SELinux Context is mismatched, use the restorecon –R /var command

3. service httpd start|restart

4. chkconfig httpd on

Order allow, deny  Allows explicitly allowed clients, denies everyone else; clients matched by both allow and deny are denied.

Order deny, allow  denies explicitly denied clients, allows everyone else, clients matched by both allow and deny are allowed.